Synthesis, biological properties, and molecular modeling investigation of the first potent, selective, and water-soluble human A(3) adenosine receptor antagonist

J Med Chem. 2002 Aug 15;45(17):3579-82. doi: 10.1021/jm020974x.


A new, highly potent, selective, and water-soluble antagonist of the hA(3) adenosine receptor was synthesized and tested in binding and functional assays. Compound 4 (5-[[(4-pyridyl)amino]carbonyl]amino-8-methyl-2-(2-furyl)-pyrazolo[4,3-e]1,2,4-triazolo[1,5-c]pyrimidine hydrochloride) displayed high water solubility (15 mM) and the highest affinity (K(i) = 0.01 nM) and selectivity for the hA(3) versus A(1), A(2A), and A(2B) receptors (>10000-fold) ever reported. A Schild analysis of the antagonism by 4 of agonist-induced inhibition of cAMP production in CHO cells expressing the hA(3) receptor indicated a K(B) value of 0.20 nM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cricetinae
  • Humans
  • Models, Molecular
  • Purinergic P1 Receptor Antagonists*
  • Pyrimidines / chemical synthesis*
  • Pyrimidines / chemistry
  • Pyrimidines / pharmacology
  • Receptor, Adenosine A3
  • Receptors, Purinergic P1 / metabolism
  • Solubility
  • Structure-Activity Relationship
  • Triazoles / chemical synthesis*
  • Triazoles / chemistry
  • Triazoles / pharmacology


  • 5-(((4-pyridyl)amino)carbonyl)amino-8-methyl-2-(2-furyl)pyrazolo(4,3-e)1,2,4-triazolo(1,5-c)pyrimdiine
  • Purinergic P1 Receptor Antagonists
  • Pyrimidines
  • Receptor, Adenosine A3
  • Receptors, Purinergic P1
  • Triazoles